| In the first part of the thesis, the controlled free radical polymerization of N-isopropylacrylamide (NIPAM) via Reversible Addition-Fragmentation Chain Transfer process (RAFT) was achieved using two different trithioesters as chain transfer agents namely S,S'-bis(alpha,alpha'-dimethyl-alpha"-acetic acid)-trithiocarbonate, (CTA1), and 2-dodecylsulfanylthiocarbonylsulfanyl-2-methyl propionic acid, (CTA2). Poly(N-isopropylacrylamide) P(NIPAM) with predictable molar masses and narrow polydispersities were obtained. The aqueous solution properties of the RAFT synthesized P(NIPAM) was further investigated as a function of molecular weights, concentration, and in the presence of water soluble macromolecular species such poly(ethylene glycol) and bovine serum albumin. As expected, the lower critical solution temperature (LCST) of P(NIPAM) was found to decrease with increasing molecular weights, concentrations and increase with increasing concentration of water soluble macromolecular species. The coil to globular transition of relatively low molecular weight P(NIPAM) was found to be the most affected by the presence of water-soluble macromolecular species.;For the third part of the thesis, we have explored the direct synthesis of protein stabilized gold nanoparticles via a direct and simple photochemical process. Bovine serum albumin (BSA) stabilized gold nanoparticles were synthesized in one step, using Irgacure (I-2959) as photoinitiator. UV radiation facilitated the easy one step synthesis of protein stabilized gold nanoparticles without any denaturation of the protein, during the process. We have also studied the effect of increasing concentration of BSA on the core size and polydispersity of gold nanoparticles. Dynamic Light Scattering (DLS) data and Transmission Electron Microscopy (TEM) images have confirmed the presence of relatively monodisperse gold nanoparticles. The polydispersity of mixed monolayer stabilized gold nanoparticles were found to be largely dependent on the concentration of BSA in mixed monolayer. UV visible spectrum obtained for mixed monolayer stabilized gold nanoparticles revealed aggregation with the increase in BSA content. The stability of gold nanoparticles was determined by critical coagulation concentration determination, which confirmed the presence of stable nanoparticles in high salt conditions. Finally, Polyacrylamide Gel Electrophoresis (PAGE) and fluorescence spectrum have confirmed that BSA was not denatured during the photochemical process and it still possesses its native conformation.;In the second part of this work, glycopolymers containing free hydroxyl groups were prepared by a versatile RAFT polymerization method. The glycomonomers were synthesized by a very facile synthetic approach. The glycopolymers were obtained in high yield after purification of controlled dimensions as determined by GPC. Furthermore, two types of glycopolymers were prepared containing either open or cyclic form of carbohydrate residues as pendent groups. The in-situ reduction of the glycopolymers and gold tetraaureate resulted in the formation of highly stable modified gold nanoparticles with diameters ranging from 40 to 80 nm in aqueous media. Multifunctional glyconanoparticles were also generated in the presence of varying amounts of biotinylated-polyethyleneglycol ( bio-PEG-SH) having terminal thiol groups. The gold nanoparticles underwent aggregation in the presence of streptavidin as revealed by UV-visible spectroscopy. The availability of the biotin for conjugation to streptavidin was also confirmed using surface plasmon resonance (SPR). |
